Thursday, 11 October 2007

The first Astronaut for Malaysia: Looking at space travel

Malaysia's first 'angkasawan' (astronaut) Dr Sheikh Muszaphar Shukor, lifted off at 9.21pm Malaysian time yesterday in the Soyuz-TMA-11 spacecraft in the Expedition 16 led by Commander Peggy Whitson and assisted by Flight Engineer Yuri Malenchenko. They will dock to the Earth-facing port of the International Space Station’s Zarya module on Friday about 10:52 a.m.With all the excitement about adventure in space research, I looked at some interesting articles about space travel and the human body.

Space flight is associated with the loss of skeletal muscle, principally from muscles with anti-gravity functions. Examination of data across different missions can permit a distinction to be made between true microgravity responses and what are mission-specific responses. Protein metabolism has been investigated on six missions, four short-term [Shuttle missions Space Life Sciences 1 (1991, SLSI), Space Life Sciences 2 (1993, SLS2), Deutsche-2 (1993, D2) and the Life and Microgravity Sciences (1996, LMS)] and two long-term missions (Skylab 1993 and NASA/MIR, 1996-1998). Measurements made include dietary intake (six missions), nitrogen balance (four missions), whole-body protein kinetics with [15N]glycine as the tracer (four missions) and cortisol excretion (three missions). Also available for comparison are bed rest studies with and without exercise. The purpose of this paper is to see what can be learnt about the muscle loss problem by comparing metabolic results across the six missions for which data are available and against bed rest. The analysis suggests that there is a linkage between the inability to maintain energy balance and exercise, and the connection is the decreased efficiency of removal of the metabolic by-products of exercise (heat, CO2) during space flight (Stein, 2000).

While resistance exercise should be a logical choice for prevention of strength loss during unloading, the principle of training specificity cannot be overlooked. Our purpose was to explore training specificity in describing the effect of our constant load exercise countermeasure on isokinetic strength performance. Twelve healthy men (mean +/- SD: 28.0 +/- 5.2 years, 179.4 +/- 3.9 cm, 77.5 +/- 13.6 kg) were randomly assigned to no exercise or resistance exercise (REX) during 14 days of bed rest. REX performed five sets of leg press exercise to volitional fatigue (6-10 repetitions) every other day. Unilateral isokinetic concentric-eccentric knee extension testing performed before and on day 15 prior to reambulation included torque-velocity and power-velocity relationships at four velocities (0.52, 1.75, 2.97, and 4.19 rad s-1), torque-position relationship, and contractile work capacity (10 repetitions at 1.05 rad s-1). Two (group) x 2 (time) ANOVA revealed no group x time interactions; thus, groups were combined. Across velocities, angle-specific torque fell 18% and average power fell 20% (p < 0.05). No velocity x time or mode (concentric/eccentric) x time interactions were noted. Torque x position decreased on average 24% (p < 0.05). Total contractile work dropped 27% (p < 0.05). Results indicate bed rest induces rapid and marked reductions in strength and our constant load resistance training protocol did not prevent isokinetic strength losses. Differences between closed-chain training and open-chain testing may explain the lack of protection (Bamman et al, 2000).

Space flight exerts substantial effects on fluid volume control in humans. Cardiac distension occurs during the first 1-2 days of space flight relative to supine and especially upright 1g conditions. Plasma volume contraction occurs quickly in microgravity, probably as a result of transcapillary fluid filtration into upper-body interstitial spaces. No natriuresis or diuresis has been observed in microgravity, such that diuresis cannot explain microgravity-induced hypovolemia. Reduction of fluid intake occurs irrespective of space motion sickness and leads to hypovolemia. The fourfold elevation of urinary antidiuretic hormone (ADH) levels on flight day 1 probably results from acceleration exposures and other stresses of launch. Nevertheless, it is fascinating that elevated ADH levels and reduced fluid intake occur simultaneously early in flight. Extracellular fluid volume decreases by 10-15% in microgravity, and intracellular fluid volume appears to increase. Total red blood cell mass decreases by approximately 10% within 1 week in space. Inflight Na(+) and volume excretory responses to saline infusion are approximately half those seen in pre-flight supine conditions. Fluid volume acclimation to microgravity sets the central circulation to homeostatic conditions similar to those found in an upright sitting posture on Earth. Fluid loss in space contributes to reduced exercise performance upon return to 1g, although not necessarily in flight. In-flight exercise training may help prevent microgravity-induced losses of fluid and, therefore, preserve the capacity for upright exercise post-flight. Protection of orthostatic tolerance during space flight probably requires stimulation of orthostatic blood pressure control systems in addition to fluid maintenance or replacement (Wautenpaugh, 2001).

The efficacy of a resistance exercise paradigm, using a gravity-independent flywheel principle, was examined in four men subjected to 110 days of confinement (simulation of flight of international crew on space station; SFINCSS-99). Subjects performed six upper- and lower-body exercises (calf raise, squat, back extension, seated row, lateral shoulder raise, biceps curl) 2-3 times weekly during the confinement. The exercise regimen consisted of four sets of ten repetitions of each exercise at estimated 80-100% of maximal effort.Overall, the training load (work) increased in all subjects (range 16-108%) over the course of the intervention. Maximal voluntary isometric force was unchanged following confinement. Although the perceived level of strain and comfort varied between exercises and among individuals, the results of the present study suggest this resistance exercise regimen is effective in maintaining or even increasing performance and maximal force output during long-term confinement. (Alkner et al, 2003)

Bone loss in the lower extremities and lumbar spine is an established consequence of long-duration human space flight. Astronauts typically lose as much bone mass in the proximal femur in 1 month as postmenopausal women on Earth lose in 1 year. Pharmacological interventions have not been routinely used in space, and countermeasure programs have depended solely upon exercise. However, it is clear that the osteogenic stimulus from exercise has been inadequate to maintain bone mass, due to insufficient load or duration. Attention has therefore been focused on several pharmacological interventions that have been successful in preventing or attenuating osteoporosis on Earth.(Cavanagh et al, 2005).

The objectives of this project were to investigate exercise load and body weight related to long-duration confinement in a closed environment simulating ISS flight conditions, and to evaluate subjects' motivation to continue the experiment and their adaptation to isolation. METHODS: Four Russian male subjects participated in a 240-d experiment (Group I), and four subjects (three male subjects and one female subject) from Austria, Canada, Japan, and Russia participated in a 110-d experiment (Group II). Exercise load was estimated during confinement using a modified Rating of Perceived Exertion scale. Free reports were used to determine subjects' motivation. Body weight was measured before, during, and after confinement. RESULTS: Group I achieved their lowest exercise loads during their first month of isolation; problems with adaptation to the isolation environment were also reported during this first month. Group II exercise load was significantly lower in the second month due to crewmember problems; loss of motivation could be noted from their free reports. The subject with the lowest exercise load retired from the isolation experiment earlier than scheduled. Exercise load was not correlated with prior exercise habits. Significant differences in body weight was observed between group I and II and between Russian and non-Russian subjects. One subject in Group I experienced a significant increase in his body weight. CONCLUSION: Exercise load may be a good indicator for adaptation problems and motivation changes in closed environments. Immobility, lack of space, and smoking cessation in general did not induce significant body weight changes (Kraft et al, 2003).

The system of countermeasures used by Russian cosmonauts in space flights on board of International Space Station (ISS) was based on the developed and tested in flights on board of Russian space stations. It included as primary components: physical methods aimed to maintain the distribution of fluids at levels close to those experienced on Earth; physical exercises and loading suits aimed to load the musculoskeletal and the cardiovascular systems; measures that prevent the loss of fluids, mainly, water-salt additives which aid to maintain orthostatic tolerance and endurance to gravitational overloads during the return to Earth; well-balanced diet and medications directed to correct possible negative reactions of the body to weightlessness. Fulfillment of countermeasure's protocols inflight was thoroughly controlled. Efficacy of countermeasures used were assessed both in- and postflight. The results of studies showed that degrees of alterations recorded in different physiological systems after ISS space flights in Russian cosmonauts were significantly higher than those recorded after flights on the Russian space stations. This phenomenon was caused by the failure of the ISS crews to execute fully the prescribed countermeasures' protocols which was as a rule excused by technical imperfectness of exercise facilities, treadmill TVIS particularly (Kozlovskaya et al, 2004).

The efficacy of countermeasure exercise for diminishing disturbances induced by microgravity in motor system and its visceral supply during different stages of long-duration flight was evaluated. The results of both bicycle and locomotor testing indicate that physical fitness of cosmonaut does not become worse in the course of the long-duration flight. On the contrary, the lowest fitness was recorded at the first stage of mission, just after one month of flight. The "dead period" at the beginning of space flight seems to be a manifestation of the acute decrease in physical condition on transition from 1 G to microgravity, when none of the regular countermeasure regimes is sufficiently effective and acute increase of volume and intensity of training is impossible under the conditions of space flight (Popov et al, 2004).

Find out more in the links:-
Malaysian Astronaut Programme
NASA website
Yuri Gagarin Cosmonaut Training Centre
International Space Station
ISS Research
Location of ISS
NASA-TV Schedule

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